Mechanisms Responsible for a ΦX174 Mutant's Ability To Infect<i>Escherichia coli</i>by Phosphorylation

Cox, J. Colin; Putonti, Catherine

doi:10.1128/jvi.00047-10

Cited by 5 publications

(8 citation statements)

References 22 publications

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“…5, dark gray). Like the nullifying mutation described in this study, other host range-affecting mutations map to this region (26,55).…”

Section: Figsupporting

confidence: 55%

“…Primarily residing within the coat F-spike G protein interface, they are more easily visualized when a spike complex is removed (right image). Mutations identified in X174 studies (26,55) are depicted in cyan. The residues of the conserved six-carbon sugar binding site are highlighted in purple (31)(32)(33).…”

Section: Figmentioning

confidence: 99%

“…As is typical of most enfants terribles, X174-like phages behave badly. Although they utilize only LPS as a receptor (21), host range mutations alter one of three structural proteins: the capsid, the spike, or the DNA pilot protein (22)(23)(24)(25)(26)(27). Indeed, conformational changes involving all three structural proteins have been documented during early infection (28)(29)(30).…”

mentioning

confidence: 99%

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Recessive Host Range Mutants and Unsusceptible Cells That Inactivate Virions without Genome Penetration: Ecological and Technical Implications

Roznowski

Young

Love

et al. 2019

J Virol

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Although microviruses do not possess a visible tail structure, one vertex rearranges after interacting with host lipopolysaccharides. Most examinations of host range, eclipse, and penetration were conducted before this “host-induced” unique vertex was discovered and before DNA sequencing became routine. Consequently, structure-function relationships dictating host range remain undefined. Biochemical and genetic analyses were conducted with two closely related microviruses, α3 and ST-1. Despite ∼90% amino acid identity, the natural host of α3 is Escherichia coli C, whereas ST-1 is a K-12-specific phage. Virions attached and eclipsed to both native and unsusceptible hosts; however, they breached only the native host’s cell wall. This suggests that unsusceptible host-phage interactions promote off-pathway reactions that can inactivate viruses without penetration. This phenomenon may have broader ecological implications. To determine which structural proteins conferred host range specificity, chimeric virions were generated by individually interchanging the coat, spike, or DNA pilot proteins. Interchanging the coat protein switched host range. However, host range expansion could be conferred by single point mutations in the coat protein. The expansion phenotype was recessive: genetically mutant progeny from coinfected cells did not display the phenotype. Thus, mutant isolation required populations generated in environments with low multiplicities of infection (MOI), a phenomenon that may have impacted past host range studies in both prokaryotic and eukaryotic systems. The resulting genetic and structural data were consistent enough that host range expansion could be predicted, broadening the classical definition of antireceptors to include interfaces between protein complexes within the capsid. IMPORTANCE To expand host range, viruses must interact with unsusceptible host cell surfaces, which could be detrimental. As observed in this study, virions were inactivated without genome penetration. This may be advantageous to potential new hosts, culling the viral population from which an expanded host range mutant could emerge. When identified, altered host range mutations were recessive. Accordingly, isolation required populations generated in low-MOI environments. However, in laboratory settings, viral propagation includes high-MOI conditions. Typically, infected cultures incubate until all cells produce progeny. Thus, coinfections dominate later replication cycles, masking recessive host range expansion phenotypes. This may have impacted similar studies with other viruses. Last, structural and genetic data could be used to predict site-directed mutant phenotypes, which may broaden the classic antireceptor definition to include interfaces between capsid complexes.

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“…5, dark gray). Like the nullifying mutation described in this study, other host range-affecting mutations map to this region (26,55).…”

Section: Figsupporting

confidence: 55%

Section: Figmentioning

confidence: 99%

mentioning

confidence: 99%

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Recessive Host Range Mutants and Unsusceptible Cells That Inactivate Virions without Genome Penetration: Ecological and Technical Implications

Roznowski

Young

Love

et al. 2019

J Virol

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“…) and yet differ at only 11 synonymous and 1 nonsynonymous substitutions across their 6.5 kb genomes (Supporting Information Table S3). Single non‐synonymous substitutions are known to cause differences in host range, as previously observed in ssDNA phage phiX174, dsRNA phage phi6 and dsDNA phage ϕΕΦ24Χ (Cox and Putonti, ; Uchiyama et al ., ; Ford et al ., ). Here the non‐synonymous substitution belongs to a protein located in the phage particle and thus, presumed structural (Holmfeldt et al ., ), though its specific function is still unknown.…”

Section: Resultsmentioning

confidence: 73%

“…Thus, the difference in EOI could not be connected with sequence mutations in the phages' genomes. While difference in infection driven by altered phage entry (e.g., Baranowski et al ., ; Cox and Putonti, ; Uchiyama et al ., ; Ford et al ., ) or CRISPR system (Barrangou et al ., ) function is explained by nucleotide substitutions, this is not always the case for phages circumventing host restriction‐modification systems (Krüger and Bickle, ). We therefore hypothesized that the difference in EOI seen between the passaged and ancestral phages could be due to differences in DNA modification.…”

Section: Resultsmentioning

confidence: 99%

Large‐scale maps of variable infection efficiencies in aquatic Bacteroidetes phage‐host model systems

Holmfeldt

Solonenko

Howard-Varona

et al. 2016

Environmental Microbiology

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Summary 18Microbes drive ecosystem functioning, and their viruses modulate these impacts through 19 mortality, gene transfer, and metabolic reprogramming. Despite the importance of virus-20 host interactions and likely variable infection efficiencies of individual phages across 21 hosts, such variability is seldom quantified. Here we quantify infection efficiencies of 38 22 phages against 19 host strains in aquatic Cellulophaga (Bacteroidetes) phage-host model 23 systems. Binary data revealed that some phages infected only one strain while others 24 infected 17, whereas quantitative data revealed that efficiency of infection could vary 10 25 orders of magnitude, even among phages within one population. This provides a baseline 26 for understanding and modeling intra-population host range variation. Genera specific 27 host ranges were also informative. For example, the Cellulophaga Microviridae, showed 28 a markedly broader intra-species host range than previously observed in Escherichia coli 29 systems. Further, one phage genus, Cba41, was examined to investigate non-heritable 30 changes in plating efficiency and burst size that depended on which host strain it most 31 recently infected. While consistent with host modification of phage DNA, no differences 32 in nucleotide sequence or DNA modifications were detected, leaving the observation 33 repeatable, but the mechanism unresolved. Overall this study highlights the importance of 34 quantitatively considering replication variations in studies of phage-host interactions. 35 36

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Stepwise Evolution of E. coli C and ΦX174 Reveals Unexpected Lipopolysaccharide (LPS) Diversity

Dherbey

Parab

Gallie

et al. 2023

Molecular Biology and Evolution

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Phage therapy is a promising method for the treatment of multi-drug-resistant bacterial infections. However, its long-term efficacy depends on understanding the evolutionary effects of the treatment. Current knowledge of such evolutionary effects is lacking, even in well-studied systems. We used the bacterium Escherichia coli C and its bacteriophage ΦX174, which infects cells using host lipopolysaccharide (LPS) molecules. We first generated 31 bacterial mutants resistant to ΦX174 infection. Based on the genes disrupted by these mutations, we predicted that these E. coli C mutants collectively produce eight unique LPS structures. We then developed a series of evolution experiments to select for ΦX174 mutants capable of infecting the resistant strains. During phage adaptation, we distinguished two types of phage resistance: one that was easily overcome by ΦX174 with few mutational steps (“easy” resistance), and one that was more difficult to overcome (“hard” resistance). We found that increasing the diversity of the host and phage populations could accelerate the adaptation of phage ΦX174 to overcome the hard resistance phenotype. From these experiments, we isolated 16 ΦX174 mutants that, together, can infect all 31 initially resistant E. coli C mutants. Upon determining the infectivity profiles of these 16 evolved phages, we uncovered 14 distinct profiles. Given that only eight profiles are anticipated if the LPS predictions are correct, our findings highlight that the current understanding of LPS biology is insufficient to accurately forecast the evolutionary outcomes of bacterial populations infected by phage.

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Mechanisms Responsible for a ΦX174 Mutant's Ability To InfectEscherichia coliby Phosphorylation

Cited by 5 publications

References 22 publications

Recessive Host Range Mutants and Unsusceptible Cells That Inactivate Virions without Genome Penetration: Ecological and Technical Implications

Recessive Host Range Mutants and Unsusceptible Cells That Inactivate Virions without Genome Penetration: Ecological and Technical Implications

Large‐scale maps of variable infection efficiencies in aquatic Bacteroidetes phage‐host model systems

Stepwise Evolution of E. coli C and ΦX174 Reveals Unexpected Lipopolysaccharide (LPS) Diversity

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